1. the older style potentiometers that required headers, wiring, and holes drilled through the circuit board are now replaced by pcb-mount style potentiometers. I’ve tried really hard to get it right, so I’m hoping I did.

2. fader mounting holes are resized to be the correct size… or.. a better size. I’d made an error on the v3.1 boards in forgetting to fix the problem I saw on the v3 boards. So they should go in easy peasy now.

3. mounting holes are going to be fabricated by the board house. It took me a while to figure out that I can get them to do that for me. The net result is that a significant amount of work will be reduced to a couple of machining operations once I get the boards. The cost to get them to do the final machining operations was far outweighed by my ability to do it on my bandsaw in no time.

4. Electrical testing. This extra board house option will further increase my confidence in the product I sell. I could test the boards myself, but I’d rather be working on more creative things. I figured it was best to leave this important step up to people who are experts at quality control.